Modern driver assistance systems often use sensor equipment that can accurately sense objects in all three spatial dimensions. Numerous downstream functions are based thereon, for example a distance-sensing cruise control system, a parking aid, a lane-keeping assistant, a traffic sign recognition system, a lane departure warning system, and others. Light-based, in particular laser-based, sensor suites, called “laser scanners” or “lidar” or “ladar,” are well suited for such tasks.
Particularly robust and inexpensive micromirrors, i.e., micromechanical mirrors, are advantageously used for this. Light scanners or laser scanners having such micromechanical mirrors are also called “micromirror scanners” or “micromirror laser scanners.” Technical challenges are presented by the limited thermal tolerance of the light sources that are used (for example laser diodes, LEDs). The number of image points in one scanning operation, or per unit time, is thereby limited. In conventional systems, the angular resolution can correspondingly turn out to be comparatively low.
U.S. Pat. No. 5,638,164 describes a method for controlling a laser scanner in which a scene is scanned with laser beams.
The laser beams are emitted according to a regular grid of points, and the reflectivity of objects that the light beams strike is determined. If a region is classified as “of interest” according to reflectivity, the grid spacing of the regular point grid can be reduced in order to investigate the region “of interest” in more detail.